1. Field of the Invention
The present invention relates to a data structure that allows data whose decoding time is specified for each predetermined unit to be played back in a playback apparatus without disturbing processing in a decoder buffer, and a recording medium on which the data structure is recorded. The invention also relates to an authoring apparatus, method, and program for generating the data structure, a recording apparatus, method, and program for recording the data structure on the recording medium, a verification apparatus, method, and program for verifying whether generated data satisfies certain conditions, and a manufacturing apparatus and method for manufacturing the recording medium.
2. Description of the Related Art
As the standards of disc-type recording media which are removable from recording/playback apparatuses, Blu-ray Disc standards have been proposed. According to the Blu-ray Disc standards, 12-cm discs having a cover layer of 0.1 mm are used as recording media, and objective lenses having a blue-violet laser of a wavelength of 405 nm and an numerical aperture of 0.85 are used as optical systems so that a maximum of 27 gigabytes (GB) recording capacity is implemented. This makes it possible to record Japanese-standard broadcasting satellite (BS) digital high-definition (HD) programs for more than two hours without deteriorating the image quality.
As the sources for supplying audio/video (AV) signals to be recorded on such optical discs, two types of sources are assumed: one type is a source for supplying analog signals transmitted by analog television broadcasting and the other type is a source for supplying digital signals transmitted by digital television broadcasting. According to the Blu-ray Disc standards, the standards for recording AV signals by the two types of broadcasting systems have already been defined.
As the derivative standards of the current Blu-ray Disc, read-only recording media on which movies or music are recorded are being developed. As disc-type recording media for recording movies or music, digital versatile discs (DVDs) have already been used widely. However, read-only optical discs based on the Blu-ray Disc standards are superior to known DVDs since they can record HD video for more than two hours while maintaining the high image quality by taking advantage of characteristics unique to the Blu-ray Disc, such as the large capacity and high transfer speed.
The standards of read-only recording media based on Blu-ray Disc are hereinafter referred to as the Blu-ray Disc Read-Only Memory Format (BD-ROM) standards.
One of the indispensable elements for the content recorded on read-only recording media is subtitles. In the BD-ROM standards, subtitles are displayed on a plane different from a plane on which a moving picture is displayed, and by combining the subtitle plane with the moving picture plane, the subtitles and the moving picture can be displayed by being superposed on each other. For example, the subtitle plane is overlaid on the moving picture plane, and in the subtitle plane, the portions other than the subtitles are made transparent. Then, one piece of image data in which subtitles are displayed on a moving picture can be formed.
To record the content, such as a movie, on a disc and offer the disc for sale as a package media, a user interface for controlling the execution of various programs that accompany the content is recorded together with the content on the disc. A typical user interface is a menu displayed on a screen. As an example of a menu displayed on a screen, buttons for selecting functions are provided as a button image, and the user can select and set one of the buttons through a predetermined input unit, and then, the function assigned to the selected button is executed. Generally, by using a cross key provided for a remote control commander compatible with a player, the user selects a button displayed on a screen and presses a setting key. Then, the function associated with the button is executed.
Japanese Unexamined Patent Application Publication No. 2004-304767 discloses the following techniques. In the technique disclosed in this publication, on the basis of recording/playback standards, i.e., the Blu-ray Disc standards (Blu-ray Disc Rewritable Format Ver1.0), a moving picture plane for displaying a moving picture and a subtitle plane for displaying subtitles are separately provided. Then, the moving picture based on video data and the subtitles based on subtitle image data are displayed together on one screen. Additionally, a technique for displaying a menu on a screen by the use of a button image is also disclosed.
Subtitle image data or menu screen display data includes information concerning the structure of data, attribute information concerning the attributes of data, real data, and information indicating the end of data, which are divided by the breakpoints intended by the author. In each of the above-described data items, the decoding time is specified. The output time may also be specified. That is, such information is read from a disc and is supplied to a decoder, and is temporarily stored in a decode buffer. Then, each information item is read out from the decode buffer at the specified decoding time and is decoded. The decoded information item is then stored in an output buffer. The information decoded and stored in the output buffer is then output at the specified output time.
It is assumed that a decoder is provided for each of subtitle image data and menu screen display data.